Four channel PRBS generator

Four channel PRBS generator: A Flexible User Friendly Four Channel PRBS Generator

A new product release by ADSASNTEC Inc. is a 0.1-40Gb/s four channel pseudorandom binary sequence (PRBS) generator featuring custom word functionality. The two choices for PRBS pattern lengths at the output are PRBS 27-1 (PRBS7) and PRBS 211-1. Up to 1.0Mbit customized data words can also be programmed in to replace the PRBS patterns at the output. Application areas included test and measurement (T&M) and R&D.

The flexible architecture of the design allows each channel to output a separate data type if desired; however they will all run at the same frequency. To provide an example, output one can deliver PRBS11, output two user selected data word, while outputs three and four can output PRBS7. Not only will all four outputs run at the same frequency, they will also all be phase aligned. This means that the data crossing points of each output data stream will line up in the time domain. CML logic is supported at the differential output data ports that are back terminated with 50Ω resistors. Output amplitude is 1.0V differential peak to peak for each of the four outputs. They also feature rise and fall times of <6.0ps.

An external clock source is needed for the 4 channel pattern generator to operate (i.e. there is not internal clock source). The clock only needs to be half the rate of the desired output data rate. For example, a 10GHz input clock will produce 20Gb/s data at the four outputs. To accept this outside clock source, the four channel PRBS generator includes a single-ended input port that is terminated with a 50Ω resistor. External clock signals can have a range of amplitudes form 0.1 to 1.0V peak to peak and should be AC coupled in.

A version of the applied external clock signal is provided as a single-ended AC coupled output on the generator to give the user the option to use. The output clock features amplitude of 400mV peak to peak and 5ps rise and fall times. To synchronize an oscilloscope, a reduced frequency version of the input clock is also outputted. The user has the option to select the division ratio of this lower speed clock. The choices are C/N where C is the frequency of the high speed input clock and 4≤N≤1024, with N being a multiple of two.

An extremely friendly graphical user interface (GUI) is supplied with the unit so the user can easily manage the system and make adjustments where and when needed. A simple USB connection is needed to link up the four channel PRBS generator with a PC to run the software and a standard plug that can be inserted into any common power outlet is used to power the product.

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